A World Cup winner who succeeded brother Bobby as FWA Footballer of the Year in 1967, ’Big Jack' joined Boro in his first managerial role following his retirement from playing in 1973.

He reportedly worked without a contract on a salary of £10,000 a year, despite the club being willing to pay much more for his services.

Typically, one of his first jobs was to oversee the re-painting of Ayresome Park in the hope of making it more attractive to fans for the new season, while he would also introduce the famous white band to Boro's red shirts as a marker of identity. 

Promotion was secured with eight games remaining of the 1973/74 season with a 1-0 win at Luton Town. The title was won by a record 15-point margin, when a win was only worth two points, and Jack was named Manager of the Year. It was the first time a manager outside of the top flight had ever won the award.

The following season, Boro finished in seventh place in the First Division, only missing out on European football on the final day of the season. The year after that, Boro finished 13th, winning the Anglo-Scottish Cup.

Jack eventually parted company with the club at the end of the 1976/77 season, citing four years as being the optimum time to spend with one group of players and suggesting that the team had peaked - though he would later write in his autobiography that he wished he had stayed longer, believing he could have brought the First Division title to the club with a few additional signings.

He did return to Boro in 1984, replacing Malcolm Allison and charged with keeping the club in the second tier. He was successful in his quest - Boro finished 17th, seven points clear of relegation.

Jack, who had received an OBE in 1974, was awarded honorary Irish Citizenship and made a freeman of the city of Dublin in 1996. Other honours included being inducted into the English Football Hall of Fame in 2005, and being named in the PFA Team of the Century in 2007.